In control systems having rotating shafts, shaft speed and applied torque are often monitored. Initially, when measuring torque on a rotating shaft, one or more “strain gauge” type sensors were physically attached to the surface of the shaft. By monitoring the resistance of the stain gauges, the torque applied to the shaft may be determined. Unfortunately, “strain gauge” type sensors proved to be relatively unstable and unreliable.
Subsequently, non-contact type torque sensors were developed for measuring torque on rotating shafts having a plurality of oppositely-magnetized, circumferential regions. Typically, under a torque load, torsional twisting of the rotating shaft occurs, resulting in the normally circumferential lines of magnetic flux (present on the rotating shaft) becoming increasingly helical as the torque load is increased. Accordingly, by measuring the axial component of the magnetic field of the rotating shaft, the torque experienced by the rotating shaft may be measured.